At what stage will the following 'max out' BHP wise?

750cc Injectors - at normal fuel pressure, and +0.5bar or what ever is safe.

NGK #7 Spark Plugs

Walbro 255 fuel pump



Cheers

 

Friend has 330bhp i believe.....for more you need different turbo.

 

750cc will be maxed at 100% IDC with normal fuel pressure at 550bhp(maybe little more),i'm running 650cc which are rated to 480-490bhp at 100% IDC
Walbro 255 fuel pump is rated to 520bhp,but i've seen failed at 450bhp,i have one plus with Bosch 044


Jura

 

5.6bhp per 1cc/min fuel flow rate, so as yuriy says 535ish bhp

 

^^^^ sorry i can't do the sums. 5.6 x 750cc /4 is 1050hp. what the right formula?

 

I think is 750x4=3000/5.25=571bhp





Jura

 

What increase do u get for upping the fuel pressure? And is it safe?

Will need to replace the walbro too I think!

 

RE: Injectors, what is the correct formula to work it out? As Jura's 571 would be ideal, but 535 is cutting it too fine.

 

Have look at this quote

https://www.scoobynet.com/showpost.p...postcount=1756



Jura

 

But not sure,how many cc will actually flow 750cc...

You are planning run NOS,Methanol or E85?



Jura

 

Thanks for the link, I remember reading about that now!

I will eventually run Meth I think, but originally just V-Power.

 

Have look on this similar figures from injectors.

http://www.scoobypedia.co.uk/index.p...rFromInjectors


But i would suggest FPR will be good additions.



Jura

 

I've got a FPR.

I will check the link out, cheers.

 

Also, is it a bad thing running the injectors at 100% duty, or is it best not to?

 

In my view,its not the best,but this depend which turbo you want run in future,but you have FPR with which you can go further..




Jura

 

I hope so! all efi cars do

 

Mean't aftermarket one

 

Chris I have a spare 290lph walbro pump down at pennine subaru, if you are needing one sure we can work something out

 

Thanks for the offer Banny I've actually just ordered a new HRC one!

 

You need some head room in your injectors or you might end up in a situation where the fuel mixture leans out. For example cold day, with a slight boost spike - if your injectors are already running 100%, they can't inject more fuel to compensate for the denser air and extra boost so the mixture goes lean...

Anders

 

Oh yeah, that makes sense

 

when i map cars i aim for max 85% duty cycle on the injectors

 

Hmmmm, well hopefully I will be aiming for 520ish.

Will my injectors be too small in theory then? If so will upping the fuel pressure by 0.5 bar help matters safely?

 

They should be ok, at 3bar fuel pressure on 740s I ran 520 quite comfortably

 

Nice one, thanks. Suppose if it does become an issue, the pressure can be cranked up on the day.

 

Also, what effect will adding methanol have on the injectors?

 

You have to run more fuel with meth so they need to be able to flow more.